Penta (GM) 4.3L marine engine; problems - they sent me these test results.

[monster1]

I'm getting an abnormal engine noise in my volvo penta 4.3gxi. While searching for the source of the noise, I noticed the engine was a quart low on oil, so I added a quart of MMO to see if it would quiet down or make the noise go away. It did not. I took it to the shop not wanting to mess around with an engine possibly getting ready to come apart. They did a UOA and sent me these results. They noted fuel dilution is at 10%. I'm assuming it's high because of the MMO. Can you guys read the results to me? Have no idea what I'm looking at. Thank you.

 

[Rand]

MMO is good.... For thinning your oil and diluting its additive pack just incase its too powerful!

Change the oil and resample at half interval.. you cant tell much from the UOA because the MMO compromised the results.

 

[PontiacHO]

Can’t help you with the lab results. On outboards (4 stroke) fuel dilution is typically caused by incorrect prop pitch.

 

[DuckRyder]

Its a GM 4.3 Vortec with EFI right?

My guess would be fuel injector(s) - quick google says the fuel pressure regulators were painted inside and the paint can come off, there was apparently a TSB to remove the screen in the regulator which it seems would just let the paint clog the injector and potentially hold it open.

The report is hard to read but 10% is a LOT of fuel. Iron looks high too depending on hours.

 

[Rand]

The report is hard to read

yes when bitog resizes the photo of the UOA I cant read it. or barely.

 

[dnewton3]

Fe and Si may point to an ingestion issue. I'm not familiar with how well boats use air filtration; you might check that.
The Na and K point to a possible coolant intrusion issue. (or are these some MMO residual?)
The fuel is high; 10% is too much regardless of what engine make and model it is.

I don't know what MMO consists of, but it's not a good thing to throw in additives and then try to discern potential issues, as the unknowns pretty much make a mockery of anything you try to figure out.

 

[fantastic]

Silicon is elevated higher than where it should be. Do you know how many hours were on this sample?

 

[monster1]

Thanks for the information. I sent a sample off to Blackstone (pre MMO). I'll post those results with more information when I get them back.

 

[kschachn]

Thanks for the information. I sent a sample off to Blackstone (pre MMO). I'll post those results with more information when I get them back.

Unfortunately that won't help in determining any potential fuel dilution.

 

[monster1]

Unfortunately that won't help in determining any potential fuel dilution.

The report from Cat is with the oil treated with MMO. The Blackstone report will not be. Are you saying the numbers will be the same? If I remember correctly, Blackstone reports are more thorough as well.

 

[spasm3]

I'm curious about how they took the sample. If they cranked it up and shut it down, and it never got warm or hot, that could be an explanation for the fuel dilution.

 

[monster1]

Its a GM 4.3 Vortec with EFI right?

My guess would be fuel injector(s) - quick google says the fuel pressure regulators were painted inside and the paint can come off, there was apparently a TSB to remove the screen in the regulator which it seems would just let the paint clog the injector and potentially hold it open.

The report is hard to read but 10% is a LOT of fuel. Iron looks high too depending on hours.

Yeah. They decided painting the inside of the fuel pumps was a good idea to keep corrosion from E10 at bay. The paint disintegrates sending those paint chips through the fuel rail and into the injectors. I replaced the damaged fuel pump years ago with a "revised" factory pump. It started giving me issues a few years later. Pulled that one apart to find the same paint goo and paint chips in the fuel rail again. I cleaned all the components down to the metal and reinstalled with a fresh rebuild kit. Trouble free since. I still pull the screen on the fuel pressure regulator every season to make sure it isn't plugged up. First time I pulled it, it was clogged with paint chips. Volvo Penta's solution is to get rid of the screen and reinstall with an E clip. I'm sure the injectors have seen some paint chips, but I haven't pulled them to be sent in for cleaning because the boat runs so well.

 

[monster1]

I'm curious about how they took the sample. If they cranked it up and shut it down, and it never got warm or hot, that could be an explanation for the fuel dilution.

Yeah. Me too. Especially since I never told them how many hours were on the oil, what weight and type oil, etc.

 

[kschachn]

The report from Cat is with the oil treated with MMO. The Blackstone report will not be. Are you saying the numbers will be the same? If I remember correctly, Blackstone reports are more thorough as well.

In terms of fuel dilution Blackstone is not capable of making an accurate measurement due to their estimation method from flash point. It only matters if that’s one of the values you’re interested in.

 

[monster1]

In terms of fuel dilution Blackstone is not capable of making an accurate measurement due to their estimation method from flash point. It only matters if that’s one of the values you’re interested in.

CAT recommended an oil change and retest at 1/2 the scheduled OCI. I guess I'll go that route if I can't get Blackstone to give an accurate test for that value. But I'll call them Monday morning to see if they can. They probably haven't got to my sample yet.

 

[kschachn]

CAT recommended an oil change and retest at 1/2 the scheduled OCI. I guess I'll go that route if I can't get Blackstone to give an accurate test for that value. But I'll call them Monday morning to see if they can. They probably haven't got to my sample yet.

They can’t. The ASTM test they use is an estimation. It is much more of a screening test than an accurate valuation of fuel. You need to use a lab that makes a direct measurement.

 

[JimPghPA]

Yeah. They decided painting the inside of the fuel pumps was a good idea to keep corrosion from E10 at bay. The paint disintegrates sending those paint chips through the fuel rail and into the injectors. I replaced the damaged fuel pump years ago with a "revised" factory pump. It started giving me issues a few years later. Pulled that one apart to find the same paint goo and paint chips in the fuel rail again. I cleaned all the components down to the metal and reinstalled with a fresh rebuild kit. Trouble free since. I still pull the screen on the fuel pressure regulator every season to make sure it isn't plugged up. First time I pulled it, it was clogged with paint chips. Volvo Penta's solution is to get rid of the screen and reinstall with an E clip. I'm sure the injectors have seen some paint chips, but I haven't pulled them to be sent in for cleaning because the boat runs so well.

Small paint chips could make the fuel injectors leak when they should be closed which could add to your fuel dilution problem. As a matter of fact it might be the cause of your fuel dilution problem. Maybe it's time to replace those injectors. I think whoever had the bright idea to paint something in a fuel system should be paying for all of the repairs you've had to occur since then.

 

[cryptolyme]

i really can't read that report at all. it's just a blur.

 

[monster1]

Got my UOA back from Blackstone. This sample had no MMO mixed in so there isn't much fuel dilution like the one the shop sent to CAT.

 

[himemsys]

Got my UOA back from Blackstone. This sample had no MMO mixed in so there isn't much fuel dilution like the one the shop sent to CAT.

View attachment 207651

How did you get a sample without MMO in it? I thought you poured the MMO in the sump, which means the whole sump has it.

Unfortunately, Blackstone does not use an accurate method (gas chromatography) for measuring fuel dilution, so you can't really compare this sample to the first one. Blackstone infers fuel dilution from the flashpoint, and is very conservative in their inference. So the same sample tested by BS and a lab that uses gas chromatography will show huge differences, with BS always having the lower result.